The Canadian Press
Published Thursday, December 13, 2012 9:53AM EST
Last Updated Thursday, December 13, 2012 8:57PM EST

OTTAWA -- Four cases of E. coli infection have prompted a recall of frozen hamburgers across the country.

The Canadian Food Inspection Agency and Loblaw Companies Ltd. are warning the public to avoid certain Butcher's Choice Garlic Peppercorn Beef Burgers because of possible contamination.

The affected product is sold frozen in 1.13 kilogram packages with a best-before date of March 3.

Public Health officials notified the CFIA on Dec. 5 that the E.coli cases could possibly be linked to a food source, which prompted the investigation into the meat.

It's not yet known, however, whether the E. coli strain responsible for the illnesses is the same as the one found in the meat.

Officials said they are also inspecting Cardinal Meat Specialist Ltd., the facility where the burgers were produced.

Loblaw Companies Ltd. of Brampton, Ont., is voluntarily recalling the affected product and the CFIA is monitoring the effectiveness of the recall.

"An initial review of inspection reports and company documentation has not identified any issues with the facility's E. coli O157 control measures and the company currently has no outstanding corrective action requests," said Garfield Balsom, a food safety recall specialist with the Canadian Food Inspection Agency.

There is a possibility that additional products could be identified and the recall could expand.

"There is good evidence these four cases are linked to some kind of common source, (but) we don't yet know what that common source is," said Dr. Frank Plummer, chief science officer at the Public Health Agency of Canada's national microbiology laboratory.

The cases identified in this investigation do not share the same genetic fingerprint as those from an outbreak earlier this year that led to a massive international beef recall, said Dr. Gregory Taylor with the Public Health Agency of Canada.

"To put it clearly, this means that these cases are not linked to the XL Foods investigation," he said.

In September, Canadian authorities were notified by their U.S. counterparts that beef from the XL Foods plant in Alberta was testing positive for E. coli.

It took the CFIA nearly two weeks after that to begin notifying the public about the products and more than eight recalls were eventually issued covering over 200 products.

The plant's license was also temporarily suspended for failing to comply with food safety measures.

The company resumed operations in late October but was only allowed to resume exports to the United States earlier this month.